Vitamin D2 (Ergocalciferol) vs Vitamin D3
Two forms of the same compound. What differs is how much of it your body absorbs, how well you tolerate it and what it costs per month.
Side by side
Green marks the better value| Vitamin D2 (Ergocalciferol) | Vitamin D3 | |
|---|---|---|
| Absorption score | 60/100 | 85/100 |
| Safety rating | 8/10 | 9/10 |
| Cost per month | $15 | $8 |
| Daily dose | 2000-4000 IU | 1000-2000 IU |
| Best timing | Morning with fat | Morning with fat |
| Evidence level | A | A |
Verdict
Vitamin D3 wins on 3 of the measurable metrics.
It scores 85/100 against 60/100 on absorption, which is what decides how much of the dose actually reaches you.
What actually differs
Vitamin D2 (Ergocalciferol)
Plant-derived form of vitamin D that's vegan-friendly but less potent than vitamin D3
- Vegan-suitable
- Plant-derived
- Ethical choice
- Available by prescription
- Less potent than D3
- Shorter duration
- More expensive
- May compete with D3
Vitamin D3
Essential hormone-like vitamin crucial for bone health and immune function
- Most studied form
- Identical to skin production
- High absorption
- Needs fat for absorption
- Slower conversion
What clashes
Vitamin D2 (Ergocalciferol) → Vitamin D3
Competition for vitamin D-binding protein · moderateWhat helps
Vitamin D2 (Ergocalciferol) → Vitamin D3
Activates vitamin K-dependent proteins · level BVitamin D3 → Vitamin D2 (Ergocalciferol)
Activates matrix Gla protein and osteocalcin · level BWhat each form is for
Same compound, but the dose, the ceiling and the record differVitamin D2 (Ergocalciferol) — vegan bone & immune support.
Usual daily dose 2000-4000 IU, taken morning with fat. The ceiling is 100 mcg (4000 IU) a day (NIH ODS). It is named as the suspect product in 276 FDA reports. Evidence grade A.
Vitamin D3 — bone health & immune support.
Usual daily dose 1000-2000 IU, taken morning with fat. The ceiling is 100 mcg (4000 IU) a day (NIH ODS). It is named as the suspect product in 276 FDA reports. Evidence grade A.
How these numbers are read
- The absorption score ranks forms of the same compound against each other. It is not a measured share of the dose — see how we derive it.
- Safety rating reflects tolerance at normal doses, not toxicity risk.
- Cost is per month at the typical daily dose, so a cheaper form taken at double the dose is not cheaper.
- Evidence level A means the form itself was studied, not just the parent compound.
Where to buy
Both forms deliver the same compound — pick by the numbers above, then check the label matches.
Affiliate links — we may earn a commission at no cost to you.
Common questions
Which is better, Vitamin D2 (Ergocalciferol) or Vitamin D3?
Vitamin D3 absorbs better — 85% against 60%. Absorption decides how much of the dose actually reaches you, so it usually matters more than the milligrams printed on the label.
What is the difference between Vitamin D2 (Ergocalciferol) and Vitamin D3?
Both deliver the same active compound. They differ in how well the body takes them up, how they are tolerated and what a month costs: $15 against $8.
Can you take Vitamin D2 (Ergocalciferol) and Vitamin D3 together?
You can, but there is rarely a reason to. Two forms of the same compound stack the same active dose, so the usual approach is to pick the better absorbed one and dose it properly.